Drilling apparatus



Feb. 11, 1969 R. c. CROOKE ETAL 3,426,855

DRILLING APPARATUS Filed Feb. 6, 1967 Sheet of 5 L W J5 AIME/[(49 Feb. 11, 1969 R. c. CROOKE ETAL 3,426,855

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fuzz/r m aim/5 BY /l /a Mr United States Patent 3,426,855 DRILLING APPARATUS Robert Curtis (Irooke, Corona del Mar, and Nick Knot,

South Laguna, Califl, assignors to Global Marine Inc,

Los Angeles, Calif., a corporation of Delaware Filed Feb. 6, 1967, Ser. No. 614,204

[1.5. Cl. 17357 3 Claims Int. Cl. E21c 7/04, 7/00; E21!) 3/04 ABSTRACT OF THE DISCLOSURE A well drilling apparatus employing an electric motor as the motive force for a drill string. The motor is carried for vertical movement in a derrick by a traveling block. The stator of the motor is constrained against rotation by a pair of vertical block guides while the rotor is adapted for coupling with a drill string.

Background of the invention This invention relates to art of drilling oil wells and the like and more particularly to an improved drive for a drill string.

At the present time, rotary drilling rigs are employed for both onshore and offshore well drilling. Drilling rigs are used to support and drive a string of drill pipes for the fabrication of a well. The drill string is driven by a rotary table through an elongated Kelly joint which is coupled to the upper end of the drill string for the latters rotation. A drill string is lengthened or shortened by disconnecting the Kelly joint from the string and adding or removing sections of the drill pipe. The raising or lowering of a drill string is accomplished by a traveling block connected to the string and disposed within a derrick. A winch driven cable, strung over a crown block on top of the derrick carries the traveling block. In offshore drilling, traveling block guides in the dirrick are used to prevent the traveling block from swinging when the vessel pitches or rolls.

Particularly in offshore drilling, the space available for connecting or disconnecting lengths of drill pipe to a drill string is limited which typically requires coupling or uncoupling of drill pipe in thirty foot lengths. The efficiency of a drilling operation, of course, is adversely affected by the number of connections and disconnections of drill pipe required to drill a given well. In addition, it is highly desirable to observe the stress on a drill string. If a portion of the drill string were located above the derricks floor its visual observation would discover such failures as cracks and splits, as well as excessive bending. However, conventional practice has the uppermost portion of the drill string located below the floor of the derrick making visual observation of the drill string impractical. Moreover, in offshore drilling, wave action on the drilling vessel often causes a drill string to be stressed because the string is constrained in the well hole while the vessel is relatively free of constraint. It is desirable, therefore, to have a flexible drill string to avoid undue stress.

Summary of the invention The subject invention provides an improved drill string drive which eliminates the Kelly, the rotary table, and their attendant apparatus through the use of a motor drive disposed above the derricks floor.

In general, the invention includes a derrick having means for raising and lowering a drill string. The raising and lowering means may include a traveling block supported by a cable disposed over a crown block and operated by a power winch. An electric motor, having a rotor, stator, and a casing, is disposed for vertical movement in the der- 3,426,855 Patented Feb. 11, 1969 rick for response to the raising and lowering means. The stator is constrained against rotation by, for example, the derrick while the rotor is adapted for connection to a drill string. Means are also provided for supplying electrical energy to the motor for driving its rotor and, hence, a connected drill string in rotation.

The stator is constrained against rotation in, for example, vertically-disposed block guides through torque arms fastened to the motor and slidably engaged for vertical movement in the block guides. These guides are presently used in offshore drilling rigs to prevent the traveling block from swinging due to wave action. The rotor has an axial bore in which is engaged a coupling member which also has an axial bore. The coupling member is adapted for connection to the drill string such that the members bore is in communication with the interior of the string for the introduction of drilling fluid. Preferably, the raising and lowering means includes a standard swivel block which carries the motor and has a bore that mates with the coupling members bore. Drilling fluid is then introduced through the swivels bore to the drill string. The coupling member is preferably removable from the bore of the rotor. For this purpose, mating longitudinal splines in the coupling member and the bore of the rotor are used with means provided, such as a stop ring, to prevent the removable coupling member from moving axially with respect to the rotor.

The improved rotary drilling apparatus of the present invention offers many advantages. The motive force for rotating a drilling string is provided by an electric motor which, in drilling position, is disposed above the derricks floor. The absence of the Kelly and rotary table together with the motors elevated position affords more working space for the drilling crew. In addition, the provision of the electric motor above the derricks floor makes it practical to connect or disconnect greater lengths of drill pipe to a drill string because of the absence of the Kelly joint. Moreover, observation of the uppermost part of a drill string is afforded by the invention allowing for the visual determination of cracks and leaks in the drill string as well as drill bit resistance, the latter being manifested in bending of the exposed portion of the drill string. Sensitive observation of drill bit resistance is further enhanced by the elimination of the friction forces between the Kelly and the Kelly drive. Moreover, the flexible drill string, which is a product of this invention, is particularly suitable for offshore drilling because of wave action on the drilling vessel.

These and other features, aspects and advantages of the subject invention will become more apparent from the following description, appended claims and drawings.

Brief description of the drawings FIGURE 1 is a schematic depiction of the drilling apparatus of the subject invention as it could be used on a drilling vessel;

FIGURE 2 is a partial view, partly in half section, of the preferred motor drive of the invention;

FIGURE 3 is a partial view of the motor drive of the invention coupled to a drill string; and

FIGURE 4 is a partial view showing the motor drive as it would be used for connecting or disconnecting drill pipe to a drill string.

Description 0 the preferred embodiments FIGURE 1 depicts one embodiment of the improved drilling apparatus of the invention as used on a drilling vessel. The apparatus includes a derrick 10 in which vertical block guides 12 are mounted. The derrick has a floor 14 upon which is mounted a spider 16 of standard design. The spider positions drill string 18 within derrick and, in addition, is used to hold slips which bear on drill string 18 to hold it in place when motor 20 is uncoupled from the string. Electric motor 20 is held against rotation through torque arms 21 which engage guide beams 12. The guide beams also provide a vertical track for the motor. The motor is carried by swivel block 22. Hook 24 supports block 22 through the latters bail 26. Cable 28, which is positioned over crown block 30, is driven by winch 32. Base 34 supports derrick 10 above moon pool 36. A moon pool is an opening through the vessel which communicates a drill string with a formation which is being drilled. Vessel 38 is only partially shown because it forms no part of the subject invention and is well known in the art. Pipe rack 40, the form of which is also well known, is mounted proximate derrick 10 on the deck of vessel 38. Drill pipe 42 is stored on pipe rack 40. This drill pipe is used to make up drill string 18.

FIGURE 2 illustrates motor 20 and its attendant structure in greater detail. The motor comprises a stator 50 and a rotor or armature 52 which are both contained in casing 54. Thrust bearings 56 are mounted on the stator for its vertical support by rotor 52 which in turn is carried by cable 28 as illustrated in FIGURE 1. Rotor 52 includes a hollow sleeve 58. The interior of the sleeve has a plurality of longitudinally disposed female splines. A coupling member in the form of a wash pipe 60 is disposed within sleeve 58 and coupled thereto through a plurality of male splines which mate with the sleeves female splines. The engaged splines of the sleeve and wash pipe allow the two members to turn as a unit with rotor 52. Stop ring 62 is secured to sleeve 58 and locks the wash pipe against vertical displacement with respect to the sleeve. Lower end 64 of Wash pipe 60 is adapted for coupling with the uppermost drill pipe in drill string 18 (the latter being shown in FIGURE 1). Torque arms 21 are connected to casing 54 and extend radially of the motor for sliding engagement with guide beams 12. This engagement constrains the motor against rotation while allowing it to translate longitudinally in the guides. For this purpose, bearing members 68 are provided on arms 66. These bearing members may be flat discs. The required rotational constraint for the motor is readily accomplished when the guide beams are channels; the torque arms will then rest in the trough of the channels.

Wash pipe 60 is threaded into the lower portion of swivel 70 which is of standard construction. Rotary mud hose 72 is rotatably coupled to the swivel such that its interior is in communication with longitudinal bore 74 of the swivel for the passage of drilling fluid to drill string 18. The drilling fluid is supplied from a storage space in vessel 38 to mud hose 72 in a well known manner. Coupling between hose 72 and swivel 70 is provided through slip ring 76 in a standard manner. The coupling allows the swivel to rotate with rotor 52 while the hose remains stationary. Swivel 70 is supported through a hook from a cable as illustrated in FIGURE 1. For this purpose bail 78 is pivotally connected to swivel 70. A hook, such as hook 24 of FIGURE 1, holds the bail and the swivel. The hook is rotatably coupled to its supporting cable through, for example, a slip ring. Bore 74 of swivel 70 is in communication with bore 80 of wash pipe 60 for the passage of drilling fluid through the wash pipe into the drill string.

Motor 20 is supplied with current from the ships directcurrent power supply through leads in conduit 82. These leads are connected to a source of direct current power (not shown). The motor must, of course, have sufficient power and torque to drive the drill string in rotation at a reasonable drilling rate. The power requirements for the motor, while variable to suit a particular application, should be in the neighborhood of 500 horse power at 350 revolutions per minute. The motor is preferably a direct current motor having a high torque at a low revolution rate. The motor is cooled by a source of pressurized air (not shown) through air cooling hose 84. The cooling air introduced into casing 54 also pressurizes the motor. The pressure differential between the cooling air and atmosphere provides a block against the entrance of combustible gases into the casing from the well and, hence, avoids fire and explosion hazards.

The weight load of the motor is carried by the wash pipe and ultimately the winch which vertically positions the motor with respect to the derrick floor. Rotational torque developed by motor 20 is transmitted to the drill string. The reaction component of this torque is transmitted through torque arms 21 to guide beams 12. Thus, the torque arms in cooperation with the guide beams prevent the casing and stator from rotating. FIGURES 3 and 4 depict typical methods of employing the motor drive of this invention. These figures also show certain modifications over the embodiment described in reference to FIGURE 2. For convenience and clarity of illustration, much of the supporting apparatus which cooperates with the motor has been omitted. Motor 20 is coupled to swivel 70 through wash pipe 60. To maintain the coupling of motor 29 to swivel 70, arm 88 is provided. This arm is connected to the swivel and to the stationary casing of the motor. Thus, in this embodiment, rotation of wash pipe 60 is not transmitted to swivel 70. Rotatable coupling 90 is provided for this purpose between the swivel and the wash pipe. Mud hose 72 is in communication with a bore in the swivel and in turn the interior of the drill string 18 through the bore in wash pipe 60 for the supply of drilling fluid. Drill string 18 is coupled to wash pipe 60 through a standard cross-over saver 92. Conduit 82 and cooling hose 84 are connected to the motor as described with reference to FIGURE 2. Swivel 70 is connected to hook 24 through bail 78. Spider 16 guides drill string 18 through derrick floor 14 to the well. Elevator 94 is connected to hook 24 by bail 96. Slips 98 are used, as seen in FIGURE 4, to hold drill string 18 above the derrick floor when it is disconnected from the motor. Hydraulically operated lift arm 100 is mounted on pipe rack 40 to lift drill pipe 42 into position for coupling to the motor. Backup tong 102 positions the drill pipe with respect to the motor for this coupling operation. Sling 104 is connected to elevator 94 which, during the coupling operation, is removed from the hook. Cable 106 is connected to a winch such as winch 32 shown in FIGURE 1.

The operation of the described embodiments of the invention is as follows: This description will be in terms of connecting drill pipe to a drill string already in the well. The removal of a drill string is accomplished by reversing the described operation. When coupling is required, drill string 18 is locked by slips 98 above derrick floor 14 in spider 16. The drill string is then disconnected from wash pipe 60 by disconnecting cross-over saver 92. Elevator 94 is then clamped around the lower exposed portion of wash pipe 60 and cable 106 drawn taut to tilt the motor over onto its side. The motor is then supported by cable 106 and cable 28. A new stand of drill pipe is then brought up from pipe rack 40 by lifting arm assembly 100 and is held in place by backup tong 102. The new stand is then coupled to cross-over saver 92 to wash pipe 60. Sling 104 is disconnected and the elevator removed from the wash pipe. Winch 32 lifts motor 20 and the new drill pipe stand into position above drill string 18 to couple the stand with the string. The drilling operation is standard except that power is supplied by the motor. As drilling progresses, the motor will lower in guide beams 12 until a new drill pipe stand is required.

The subject invention has been described with reference to certain preferred embodiments. The appended claims, however, should not necessarily be limited in their spirit and scope to this description.

What is claimed is:

1. An improved drilling apparatus comprising:

(a) a derrick;

(b) means for raising and lowering a drill string;

(c) a swivel having an axial bore carried by the raising and lowering means;

(d) an electric motor carried by the swivel having a casing, a rotor with an axial bore and a stator, the axial bore of the rotor having a plurality of female longitudinal splines;

(e) a coupling member adapted for connection to a drill string having an axial bore and a plurality of male longitudinal splines, the male longitudinal splines being engaged with the female longitudinal splines of the rotor for rotation therewith and the axial bore of the coupling member being in fluid communication with the axial bore of the swivel for passage of a drilling fluid through the axial bores of the swivel and coupling member to a drill string;

(f) means for preventing vertical movement of the coupling member with respect to the rotor;

(g) means for constraining the stator against rotation;

(11) means for supplying electrical energy to the motor;

and

(i) means for introducing air under pressure to the interior of the casing such that the pressure in the casing is in excess of atmospheric, whereby air from the air introduction means cools the rotor and stator as well as preventing explosive gases from entering the casing.

2. The improvement claimed in claim 1 wherein:

the derrick includes at least one block guide; and

the stator constraining means includes at least one torque arm secured to the motor, the torque arm extending laterally of the motor for sliding engagement with an associated guide.

3. The improvement claimed in claim 2 wherein the motor includes at least one thrust bearing disposed in the motor to vertically support the stator and the casing by the rotor.

References Cited UNITED STATES PATENTS 1,395,706 11/1921 Greve 17357 X 1,398,551 11/1921 Hanson 173-57 X 3,009,521 11/1961 Failing 173-57 X 3,053,330 9/1962 Arthur 17357 3,054,465 9/1962 Fish 17357 X NILE C. BYERS, JR., Primary Examiner.

US. Cl. X.R. 175195 

